Uporaba globokih evtektičnih topil za analizo vzorcev bele murve (Morus alba)

Gliha, Kaja (author), Kolar, Mitja (mentor), Kurečič, Manja (comentor)

Bela murva (Morus alba) se je zgodovinsko poleg svilogojstva na široko uporabljala kot del kitajske tradicionalne medicine. Je bogat vir bioaktivnih spojin, ki izkazujejo mnoge fizološke in farmakološke učinke. Problem predstavljajo konvencionalna organska topila, ki se uporabljajo pri njihovi ekstrakciji, saj zaradi relativne toksičnosti niso zaželjena. Potencialno zeleno alternativo predstavljajo globoka evtektična topila (DES). Cilj mojega raziskovalnega dela je bil preveriti učinkovitost izbranih DES v primerjavi s tradicionalnimi organskimi topil pri ekstrakciji bioaktivnih spojin iz bele murve. V ta namen sem razvila metodo HPLC-DAD za določanje izbranih polifenolov, pri čemer sem se omejila na galno kislino, kofeinsko kislino, p-kumarno kislino, rutin in resveratrol. V sklopu delne validacije so bili preverjeni linearnost, ponovljivost, meja zaznave, meja določitve, točnost ter selektivnost. Bioaktivne spojine so bile ekstrahirane iz vzorca vej bele murve na osnovi ultrazvočno asistirane ekstrakcije (UAE), ki je bila optimizirana z uporabo holin klorid/glicerol DES. Na podlagi rezultatov so bili določeni optimalni pogoji: molsko razmerje 1:2, 20 % dodane vode, 80 °C in 30 min. Za nadaljne ekstrakcije je bilo pripravljenih 6 različnih DES na osnovi holin klorida (ChCl) kot akceptorja vodikove vezi. Uporabljeni donorji vodikove vezi so vključevali glicerol, etilen glikol, propan-1,3-diol, butan-1,4-diol, ureo in glukozo. Kot konvencionalno organsko topilo je bil uporabljen metanol. Ekstrakti so bili pripravljeni iz vej, listov in plodov bele murve, učinkovitost ekstrakcije pa je bila ocenjena na tri različne načine. Poleg analize z razvito HPLC-DAD metodo sta bili določeni tudi skupna vsebnost fenolov (TPC) in skupna vsebnost flavonoidov (TFC). Dobljeni rezultati so pokazali, da so bili najučinkovitejši DES na osnovi polialkoholov kot donorjev vodikove vezi. Pri vejah in listih je bil to ChCl/glicerol DES, med tem ko je bil pri plodovih to ChCl/etilenglikol DES. V večini preverjenih primerov ekstrakcij polifenolov je vsaj en DES dosegel primerljivo ali višjo učinkovitost ekstrakcije kot organsko topilo razen v primeru flavonoidov, kjer so bili izkoristki DES pogosto nižji. To kaže na potencial uporabe DES kot alternativni postopek za zeleno in učinkovito ekstrakcijo polifenolnih bioaktivnih spojin iz rastlinskih materialov kot je to bela murva.

• Language: Slovenian
• Keywords: bela murva, DES, HPLC-DAD, TPC, TFC
• Work type: Master's thesis/paper
• Organization: FKKT - Faculty of Chemistry and Chemical Technology
• Year: 2024
• PID: 20.500.12556/RUL-162711
• Publication date in RUL: 26.09.2024

Secondary language

• Language: English
• Title: Use of deep eutectic solvents for the analysis of white mulberry (Morus alba) samples

Abstract

Historically, the white mulberry (Morus alba) has been widely used as part of Chinese traditional medicine, in addition to sericulture. It is a rich source of bioactive compounds that exhibit many physiological and pharmacological effects. Conventional organic solvents used in their extraction are a problem, as they are not desirable due to their relative toxicity. Deep eutectic solvents (DES) are a potential green alternative. The aim of my research work was to verify the efficiency of selected DES in comparison to traditional organic solvents in the extraction of bioactive compounds from white mulberry. To this end, I developed an HPLC-DAD method for the determination of selected polyphenols, limiting myself to gallic acid, caffeic acid, p-coumaric acid, rutin and resveratrol. As part of the partial validation, linearity, repeatability, limit of detection, limit of quantification, accuracy and selectivity were checked. The bioactive compounds were extracted from a sample of white mulberry branches by ultrasound-assisted extraction (UAE), optimised using choline chloride/glycerol DES. Based on the results, the determined optimal conditions were: 1:2 molar ratio, 20% added water, 80 °C and 30 min. For subsequent extractions 6 different DES based on choline chloride (ChCl) as hydrogen bond acceptor were prepared. The hydrogen bond acceptors used included glycerol, ethylene glycol, propane-1,3-diol, butane-1,4-diol, urea and glucose. Methanol was used as the conventional organic solvent. Extracts were prepared from the branches, leaves and fruits of white mulberry and the extraction efficiencies were evaluated in three different ways. In addition to the analysis by the developed HPLC-DAD method, total phenolic content (TPC) and total flavonoid content (TFC) were also determined. The results obtained showed that DES based on polyalcohols as hydrogen bond donors were the most efficient. In the case of branches and leaves, it was the ChCl/glycerol DES, while for fruits it was the ChCl/ethylene glycol DES. In most of the tested polyphenol extractions, at least one DES achieved comparable or higher extraction efficiencies than the organic solvent, except in the case of flavonoids, where DES yields were often lower. This indicates the potential of using DES as an alternative procedure for the green and efficient extraction of polyphenolic bioactive compounds from plant materials such as white mulberry.

• Keywords: white mulberry, DES, HPLC-DAD, TPC, TFC